/* pngwio.c - functions for data output
 *
 * Last changed in libpng 1.4.0 [January 3, 2010]
 * Copyright (c) 1998-2010 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 *
 * This file provides a location for all output.  Users who need
 * special handling are expected to write functions that have the same
 * arguments as these and perform similar functions, but that possibly
 * use different output methods.  Note that you shouldn't change these
 * functions, but rather write replacement functions and then change
 * them at run time with png_set_write_fn(...).
 */

#include "png.h"
#define PNG_NO_PEDANTIC_WARNINGS
#ifdef PNG_WRITE_SUPPORTED
    #include "pngpriv.h"

/* Write the data to whatever output you are using.  The default routine
 * writes to a file pointer.  Note that this routine sometimes gets called
 * with very small lengths, so you should implement some kind of simple
 * buffering if you are using unbuffered writes.  This should never be asked
 * to write more than 64K on a 16 bit machine.
 */

void /* PRIVATE */
png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
    if (png_ptr->write_data_fn != NULL)
        (*(png_ptr->write_data_fn))(png_ptr, data, length);
    else
        png_error(png_ptr, "Call to NULL write function");
}

    #ifdef PNG_STDIO_SUPPORTED
/* This is the function that does the actual writing of data.  If you are
 * not writing to a standard C stream, you should create a replacement
 * write_data function and use it at run time with png_set_write_fn(), rather
 * than changing the library.
 */
        #ifndef USE_FAR_KEYWORD
void PNGAPI
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
    png_uint_32 check;

    if (png_ptr == NULL)
        return;
    check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
    if (check != length)
        png_error(png_ptr, "Write Error");
}
        #else
/* This is the model-independent version. Since the standard I/O library
 * can't handle far buffers in the medium and small models, we have to copy
 * the data.
 */

            #define NEAR_BUF_SIZE 1024
            #define MIN(a, b) (a <= b ? a : b)

void PNGAPI
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
    png_uint_32 check;
    png_byte* near_data; /* Needs to be "png_byte *" instead of "png_bytep" */
    png_FILE_p io_ptr;

    if (png_ptr == NULL)
        return;
    /* Check if data really is near. If so, use usual code. */
    near_data = (png_byte*)CVT_PTR_NOCHECK(data);
    io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
    if ((png_bytep)near_data == data)
    {
        check = fwrite(near_data, 1, length, io_ptr);
    }
    else
    {
        png_byte buf[NEAR_BUF_SIZE];
        png_size_t written, remaining, err;
        check = 0;
        remaining = length;
        do
        {
            written = MIN(NEAR_BUF_SIZE, remaining);
            png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
            err = fwrite(buf, 1, written, io_ptr);
            if (err != written)
                break;

            else
                check += err;

            data += written;
            remaining -= written;
        }
        while (remaining != 0);
    }
    if (check != length)
        png_error(png_ptr, "Write Error");
}

        #endif
    #endif

/* This function is called to output any data pending writing (normally
 * to disk).  After png_flush is called, there should be no data pending
 * writing in any buffers.
 */
    #ifdef PNG_WRITE_FLUSH_SUPPORTED
void /* PRIVATE */
png_flush(png_structp png_ptr)
{
    if (png_ptr->output_flush_fn != NULL)
        (*(png_ptr->output_flush_fn))(png_ptr);
}

        #ifdef PNG_STDIO_SUPPORTED
void PNGAPI
png_default_flush(png_structp png_ptr)
{
    png_FILE_p io_ptr;
    if (png_ptr == NULL)
        return;
    io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
    fflush(io_ptr);
}
        #endif
    #endif

/* This function allows the application to supply new output functions for
 * libpng if standard C streams aren't being used.
 *
 * This function takes as its arguments:
 * png_ptr       - pointer to a png output data structure
 * io_ptr        - pointer to user supplied structure containing info about
 *                 the output functions.  May be NULL.
 * write_data_fn - pointer to a new output function that takes as its
 *                 arguments a pointer to a png_struct, a pointer to
 *                 data to be written, and a 32-bit unsigned int that is
 *                 the number of bytes to be written.  The new write
 *                 function should call png_error(png_ptr, "Error msg")
 *                 to exit and output any fatal error messages.  May be
 *                 NULL, in which case libpng's default function will
 *                 be used.
 * flush_data_fn - pointer to a new flush function that takes as its
 *                 arguments a pointer to a png_struct.  After a call to
 *                 the flush function, there should be no data in any buffers
 *                 or pending transmission.  If the output method doesn't do
 *                 any buffering of output, a function prototype must still be
 *                 supplied although it doesn't have to do anything.  If
 *                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
 *                 time, output_flush_fn will be ignored, although it must be
 *                 supplied for compatibility.  May be NULL, in which case
 *                 libpng's default function will be used, if
 *                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not
 *                 a good idea if io_ptr does not point to a standard
 *                 *FILE structure.
 */
void PNGAPI
png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
                 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
{
    if (png_ptr == NULL)
        return;

    png_ptr->io_ptr = io_ptr;

    #ifdef PNG_STDIO_SUPPORTED
    if (write_data_fn != NULL)
        png_ptr->write_data_fn = write_data_fn;

    else
        png_ptr->write_data_fn = png_default_write_data;
    #else
    png_ptr->write_data_fn = write_data_fn;
    #endif

    #ifdef PNG_WRITE_FLUSH_SUPPORTED
    #ifdef PNG_STDIO_SUPPORTED
    if (output_flush_fn != NULL)
        png_ptr->output_flush_fn = output_flush_fn;

    else
        png_ptr->output_flush_fn = png_default_flush;
    #else
    png_ptr->output_flush_fn = output_flush_fn;
    #endif
    #endif /* PNG_WRITE_FLUSH_SUPPORTED */

    /* It is an error to read while writing a png file */
    if (png_ptr->read_data_fn != NULL)
    {
        png_ptr->read_data_fn = NULL;
        png_warning(png_ptr,
                    "Attempted to set both read_data_fn and write_data_fn in");
        png_warning(png_ptr,
                    "the same structure.  Resetting read_data_fn to NULL");
    }
}

    #ifdef USE_FAR_KEYWORD
        #ifdef _MSC_VER
void * png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
{
    void* near_ptr;
    void FAR* far_ptr;
    FP_OFF(near_ptr) = FP_OFF(ptr);
    far_ptr = (void FAR*)near_ptr;

    if (check != 0)
        if (FP_SEG(ptr) != FP_SEG(far_ptr))
            png_error(png_ptr, "segment lost in conversion");

    return (near_ptr);
}
        #else
void * png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
{
    void* near_ptr;
    void FAR* far_ptr;
    near_ptr = (void FAR*)ptr;
    far_ptr = (void FAR*)near_ptr;

    if (check != 0)
        if (far_ptr != ptr)
            png_error(png_ptr, "segment lost in conversion");

    return (near_ptr);
}
        #endif
    #endif
#endif /* PNG_WRITE_SUPPORTED */